Provided by: libxml-parser-perl_2.44-2build3_amd64 bug

NAME

       XML::Parser::Expat - Lowlevel access to James Clark's expat XML parser

SYNOPSIS

        use XML::Parser::Expat;

        $parser = XML::Parser::Expat->new;
        $parser->setHandlers('Start' => \&sh,
                             'End'   => \&eh,
                             'Char'  => \&ch);
        open(FOO, '<', 'info.xml') or die "Couldn't open";
        $parser->parse(*FOO);
        close(FOO);
        # $parser->parse('<foo id="me"> here <em>we</em> go </foo>');

        sub sh
        {
          my ($p, $el, %atts) = @_;
          $p->setHandlers('Char' => \&spec)
            if ($el eq 'special');
          ...
        }

        sub eh
        {
          my ($p, $el) = @_;
          $p->setHandlers('Char' => \&ch)  # Special elements won't contain
            if ($el eq 'special');         # other special elements
          ...
        }

DESCRIPTION

       This module provides an interface to James Clark's XML parser, expat. As in expat, a
       single instance of the parser can only parse one document. Calls to parsestring after the
       first for a given instance will die.

       Expat (and XML::Parser::Expat) are event based. As the parser recognizes parts of the
       document (say the start or end of an XML element), then any handlers registered for that
       type of an event are called with suitable parameters.

METHODS

       new This is a class method, the constructor for XML::Parser::Expat. Options are passed as
           keyword value pairs. The recognized options are:

           ·   ProtocolEncoding

               The protocol encoding name. The default is none. The expat built-in encodings are:
               "UTF-8", "ISO-8859-1", "UTF-16", and "US-ASCII".  Other encodings may be used if
               they have encoding maps in one of the directories in the @Encoding_Path list.
               Setting the protocol encoding overrides any encoding in the XML declaration.

           ·   Namespaces

               When this option is given with a true value, then the parser does namespace
               processing. By default, namespace processing is turned off. When it is turned on,
               the parser consumes xmlns attributes and strips off prefixes from element and
               attributes names where those prefixes have a defined namespace. A name's namespace
               can be found using the "namespace" method and two names can be checked for
               absolute equality with the "eq_name" method.

           ·   NoExpand

               Normally, the parser will try to expand references to entities defined in the
               internal subset. If this option is set to a true value, and a default handler is
               also set, then the default handler will be called when an entity reference is seen
               in text. This has no effect if a default handler has not been registered, and it
               has no effect on the expansion of entity references inside attribute values.

           ·   Stream_Delimiter

               This option takes a string value. When this string is found alone on a line while
               parsing from a stream, then the parse is ended as if it saw an end of file. The
               intended use is with a stream of xml documents in a MIME multipart format. The
               string should not contain a trailing newline.

           ·   ErrorContext

               When this option is defined, errors are reported in context. The value of
               ErrorContext should be the number of lines to show on either side of the line in
               which the error occurred.

           ·   ParseParamEnt

               Unless standalone is set to "yes" in the XML declaration, setting this to a true
               value allows the external DTD to be read, and parameter entities to be parsed and
               expanded.

           ·   Base

               The base to use for relative pathnames or URLs. This can also be done by using the
               base method.

       setHandlers(TYPE, HANDLER [, TYPE, HANDLER [...]])
           This method registers handlers for the various events. If no handlers are registered,
           then a call to parsestring or parsefile will only determine if the corresponding XML
           document is well formed (by returning without error.)  This may be called from within
           a handler, after the parse has started.

           Setting a handler to something that evaluates to false unsets that handler.

           This method returns a list of type, handler pairs corresponding to the input. The
           handlers returned are the ones that were in effect before the call to setHandlers.

           The recognized events and the parameters passed to the corresponding handlers are:

           ·   Start             (Parser, Element [, Attr, Val [,...]])

               This event is generated when an XML start tag is recognized. Parser is an
               XML::Parser::Expat instance. Element is the name of the XML element that is opened
               with the start tag. The Attr & Val pairs are generated for each attribute in the
               start tag.

           ·   End               (Parser, Element)

               This event is generated when an XML end tag is recognized. Note that an XML empty
               tag (<foo/>) generates both a start and an end event.

               There is always a lower level start and end handler installed that wrap the
               corresponding callbacks. This is to handle the context mechanism.  A consequence
               of this is that the default handler (see below) will not see a start tag or end
               tag unless the default_current method is called.

           ·   Char              (Parser, String)

               This event is generated when non-markup is recognized. The non-markup sequence of
               characters is in String. A single non-markup sequence of characters may generate
               multiple calls to this handler. Whatever the encoding of the string in the
               original document, this is given to the handler in UTF-8.

           ·   Proc              (Parser, Target, Data)

               This event is generated when a processing instruction is recognized.

           ·   Comment           (Parser, String)

               This event is generated when a comment is recognized.

           ·   CdataStart        (Parser)

               This is called at the start of a CDATA section.

           ·   CdataEnd          (Parser)

               This is called at the end of a CDATA section.

           ·   Default           (Parser, String)

               This is called for any characters that don't have a registered handler.  This
               includes both characters that are part of markup for which no events are generated
               (markup declarations) and characters that could generate events, but for which no
               handler has been registered.

               Whatever the encoding in the original document, the string is returned to the
               handler in UTF-8.

           ·   Unparsed          (Parser, Entity, Base, Sysid, Pubid, Notation)

               This is called for a declaration of an unparsed entity. Entity is the name of the
               entity. Base is the base to be used for resolving a relative URI.  Sysid is the
               system id. Pubid is the public id. Notation is the notation name. Base and Pubid
               may be undefined.

           ·   Notation          (Parser, Notation, Base, Sysid, Pubid)

               This is called for a declaration of notation. Notation is the notation name.  Base
               is the base to be used for resolving a relative URI. Sysid is the system id. Pubid
               is the public id. Base, Sysid, and Pubid may all be undefined.

           ·   ExternEnt         (Parser, Base, Sysid, Pubid)

               This is called when an external entity is referenced. Base is the base to be used
               for resolving a relative URI. Sysid is the system id. Pubid is the public id.
               Base, and Pubid may be undefined.

               This handler should either return a string, which represents the contents of the
               external entity, or return an open filehandle that can be read to obtain the
               contents of the external entity, or return undef, which indicates the external
               entity couldn't be found and will generate a parse error.

               If an open filehandle is returned, it must be returned as either a glob (*FOO) or
               as a reference to a glob (e.g. an instance of IO::Handle).

           ·   ExternEntFin      (Parser)

               This is called after an external entity has been parsed. It allows applications to
               perform cleanup on actions performed in the above ExternEnt handler.

           ·   Entity            (Parser, Name, Val, Sysid, Pubid, Ndata, IsParam)

               This is called when an entity is declared. For internal entities, the Val
               parameter will contain the value and the remaining three parameters will be
               undefined. For external entities, the Val parameter will be undefined, the Sysid
               parameter will have the system id, the Pubid parameter will have the public id if
               it was provided (it will be undefined otherwise), the Ndata parameter will contain
               the notation for unparsed entities. If this is a parameter entity declaration,
               then the IsParam parameter is true.

               Note that this handler and the Unparsed handler above overlap. If both are set,
               then this handler will not be called for unparsed entities.

           ·   Element           (Parser, Name, Model)

               The element handler is called when an element declaration is found. Name is the
               element name, and Model is the content model as an XML::Parser::ContentModel
               object. See "XML::Parser::ContentModel Methods" for methods available for this
               class.

           ·   Attlist           (Parser, Elname, Attname, Type, Default, Fixed)

               This handler is called for each attribute in an ATTLIST declaration.  So an
               ATTLIST declaration that has multiple attributes will generate multiple calls to
               this handler. The Elname parameter is the name of the element with which the
               attribute is being associated. The Attname parameter is the name of the attribute.
               Type is the attribute type, given as a string. Default is the default value, which
               will either be "#REQUIRED", "#IMPLIED" or a quoted string (i.e. the returned
               string will begin and end with a quote character). If Fixed is true, then this is
               a fixed attribute.

           ·   Doctype           (Parser, Name, Sysid, Pubid, Internal)

               This handler is called for DOCTYPE declarations. Name is the document type name.
               Sysid is the system id of the document type, if it was provided, otherwise it's
               undefined. Pubid is the public id of the document type, which will be undefined if
               no public id was given. Internal will be true or false, indicating whether or not
               the doctype declaration contains an internal subset.

           ·   DoctypeFin        (Parser)

               This handler is called after parsing of the DOCTYPE declaration has finished,
               including any internal or external DTD declarations.

           ·   XMLDecl           (Parser, Version, Encoding, Standalone)

               This handler is called for XML declarations. Version is a string containing the
               version. Encoding is either undefined or contains an encoding string.  Standalone
               is either undefined, or true or false. Undefined indicates that no standalone
               parameter was given in the XML declaration. True or false indicates "yes" or "no"
               respectively.

       namespace(name)
           Return the URI of the namespace that the name belongs to. If the name doesn't belong
           to any namespace, an undef is returned. This is only valid on names received through
           the Start or End handlers from a single document, or through a call to the
           generate_ns_name method. In other words, don't use names generated from one instance
           of XML::Parser::Expat with other instances.

       eq_name(name1, name2)
           Return true if name1 and name2 are identical (i.e. same name and from the same
           namespace.) This is only meaningful if both names were obtained through the Start or
           End handlers from a single document, or through a call to the generate_ns_name method.

       generate_ns_name(name, namespace)
           Return a name, associated with a given namespace, good for using with the above 2
           methods. The namespace argument should be the namespace URI, not a prefix.

       new_ns_prefixes
           When called from a start tag handler, returns namespace prefixes declared with this
           start tag. If called elsewhere (or if there were no namespace prefixes declared), it
           returns an empty list. Setting of the default namespace is indicated with '#default'
           as a prefix.

       expand_ns_prefix(prefix)
           Return the uri to which the given prefix is currently bound. Returns undef if the
           prefix isn't currently bound. Use '#default' to find the current binding of the
           default namespace (if any).

       current_ns_prefixes
           Return a list of currently bound namespace prefixes. The order of the the prefixes in
           the list has no meaning. If the default namespace is currently bound, '#default'
           appears in the list.

       recognized_string
           Returns the string from the document that was recognized in order to call the current
           handler. For instance, when called from a start handler, it will give us the start-tag
           string. The string is encoded in UTF-8.  This method doesn't return a meaningful
           string inside declaration handlers.

       original_string
           Returns the verbatim string from the document that was recognized in order to call the
           current handler. The string is in the original document encoding. This method doesn't
           return a meaningful string inside declaration handlers.

       default_current
           When called from a handler, causes the sequence of characters that generated the
           corresponding event to be sent to the default handler (if one is registered). Use of
           this method is deprecated in favor the recognized_string method, which you can use
           without installing a default handler. This method doesn't deliver a meaningful string
           to the default handler when called from inside declaration handlers.

       xpcroak(message)
           Concatenate onto the given message the current line number within the XML document
           plus the message implied by ErrorContext. Then croak with the formed message.

       xpcarp(message)
           Concatenate onto the given message the current line number within the XML document
           plus the message implied by ErrorContext. Then carp with the formed message.

       current_line
           Returns the line number of the current position of the parse.

       current_column
           Returns the column number of the current position of the parse.

       current_byte
           Returns the current position of the parse.

       base([NEWBASE]);
           Returns the current value of the base for resolving relative URIs. If NEWBASE is
           supplied, changes the base to that value.

       context
           Returns a list of element names that represent open elements, with the last one being
           the innermost. Inside start and end tag handlers, this will be the tag of the parent
           element.

       current_element
           Returns the name of the innermost currently opened element. Inside start or end
           handlers, returns the parent of the element associated with those tags.

       in_element(NAME)
           Returns true if NAME is equal to the name of the innermost currently opened element.
           If namespace processing is being used and you want to check against a name that may be
           in a namespace, then use the generate_ns_name method to create the NAME argument.

       within_element(NAME)
           Returns the number of times the given name appears in the context list.  If namespace
           processing is being used and you want to check against a name that may be in a
           namespace, then use the generate_ns_name method to create the NAME argument.

       depth
           Returns the size of the context list.

       element_index
           Returns an integer that is the depth-first visit order of the current element. This
           will be zero outside of the root element. For example, this will return 1 when called
           from the start handler for the root element start tag.

       skip_until(INDEX)
           INDEX is an integer that represents an element index. When this method is called, all
           handlers are suspended until the start tag for an element that has an index number
           equal to INDEX is seen. If a start handler has been set, then this is the first tag
           that the start handler will see after skip_until has been called.

       position_in_context(LINES)
           Returns a string that shows the current parse position. LINES should be an integer >=
           0 that represents the number of lines on either side of the current parse line to
           place into the returned string.

       xml_escape(TEXT [, CHAR [, CHAR ...]])
           Returns TEXT with markup characters turned into character entities. Any additional
           characters provided as arguments are also turned into character references where found
           in TEXT.

       parse (SOURCE)
           The SOURCE parameter should either be a string containing the whole XML document, or
           it should be an open IO::Handle. Only a single document may be parsed for a given
           instance of XML::Parser::Expat, so this will croak if it's been called previously for
           this instance.

       parsestring(XML_DOC_STRING)
           Parses the given string as an XML document. Only a single document may be parsed for a
           given instance of XML::Parser::Expat, so this will die if either parsestring or
           parsefile has been called for this instance previously.

           This method is deprecated in favor of the parse method.

       parsefile(FILENAME)
           Parses the XML document in the given file. Will die if parsestring or parsefile has
           been called previously for this instance.

       is_defaulted(ATTNAME)
           NO LONGER WORKS. To find out if an attribute is defaulted please use the
           specified_attr method.

       specified_attr
           When the start handler receives lists of attributes and values, the non-defaulted
           (i.e. explicitly specified) attributes occur in the list first. This method returns
           the number of specified items in the list.  So if this number is equal to the length
           of the list, there were no defaulted values. Otherwise the number points to the index
           of the first defaulted attribute name.

       finish
           Unsets all handlers (including internal ones that set context), but expat continues
           parsing to the end of the document or until it finds an error.  It should finish up a
           lot faster than with the handlers set.

       release
           There are data structures used by XML::Parser::Expat that have circular references.
           This means that these structures will never be garbage collected unless these
           references are explicitly broken. Calling this method breaks those references (and
           makes the instance unusable.)

           Normally, higher level calls handle this for you, but if you are using
           XML::Parser::Expat directly, then it's your responsibility to call it.

   XML::Parser::ContentModel Methods
       The element declaration handlers are passed objects of this class as the content model of
       the element declaration. They also represent content particles, components of a content
       model.

       When referred to as a string, these objects are automagicly converted to a string
       representation of the model (or content particle).

       isempty
           This method returns true if the object is "EMPTY", false otherwise.

       isany
           This method returns true if the object is "ANY", false otherwise.

       ismixed
           This method returns true if the object is "(#PCDATA)" or "(#PCDATA|...)*", false
           otherwise.

       isname
           This method returns if the object is an element name.

       ischoice
           This method returns true if the object is a choice of content particles.

       isseq
           This method returns true if the object is a sequence of content particles.

       quant
           This method returns undef or a string representing the quantifier ('?', '*', '+')
           associated with the model or particle.

       children
           This method returns undef or (for mixed, choice, and sequence types) an array of
           component content particles. There will always be at least one component for choices
           and sequences, but for a mixed content model of pure PCDATA, "(#PCDATA)", then an
           undef is returned.

   XML::Parser::ExpatNB Methods
       The class XML::Parser::ExpatNB is a subclass of XML::Parser::Expat used for non-blocking
       access to the expat library. It does not support the parse, parsestring, or parsefile
       methods, but it does have these additional methods:

       parse_more(DATA)
           Feed expat more text to munch on.

       parse_done
           Tell expat that it's gotten the whole document.

FUNCTIONS

       XML::Parser::Expat::load_encoding(ENCODING)
           Load an external encoding. ENCODING is either the name of an encoding or the name of a
           file. The basename is converted to lowercase and a '.enc' extension is appended unless
           there's one already there. Then, unless it's an absolute pathname (i.e. begins with
           '/'), the first file by that name discovered in the @Encoding_Path path list is used.

           The encoding in the file is loaded and kept in the %Encoding_Table table. Earlier
           encodings of the same name are replaced.

           This function is automatically called by expat when it encounters an encoding it
           doesn't know about. Expat shouldn't call this twice for the same encoding name. The
           only reason users should use this function is to explicitly load an encoding not
           contained in the @Encoding_Path list.

AUTHORS

       Larry Wall <larry@wall.org> wrote version 1.0.

       Clark Cooper <coopercc@netheaven.com> picked up support, changed the API for this version
       (2.x), provided documentation, and added some standard package features.